Electric switch key mounting



Aug. 18, 1970 H. LANGENBERGER ET 3,

ELECTRIC SWITCH KEY MOUNTING I Filed Nov. 19, 1968 2 Sheets-Sheet 1 /NVE N TOR. kw; -7

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Aug. 18, 1970 H. LANGENBERGER ET ELECTRIC SWITCH KEY MOUNTING Filed Nov.19, 1968 R m v M M Mm a, an 0 mm Rm m R R 1/ INVENTUR.

wzv r United States Patent 07 Int. Cl. G06c 7/02 US. Cl. 235-145 6Claims ABSTRACT OF THE DISCLOSURE A spring switch key assembly for thekeyboard of an electric calculating machine having a key shaft slidablymounted in an elongated housing. Contacts are disposed in the bottom ofthe housing. A snap spring mechanism is arranged to engage a contact armwith the contacts. An angular lever is pivotally mounted in the housingand connected to the lever and mechanism wherein depression of the keycloses a circuit and the return of the key to its normal position closesa second circuit. The keyboard opening has spaced notches in opposededges thereof. The switch key housing is provided with ribs whichcooperate with the notches when the housing is mounted within theopening. A resilient member is wedged between the housing and an edge ofthe opening to retain the housing in position.

The present application is a division of the copending application Ser.No. 600,969, filed Dec. 12, 1966 by the same-named inventors, now US.Pat. No. 3,430,012.

The keyboard of an electric calculating machine contains a plurality ofkeys for the introduction of data into the calculating machine. Suchkeys are generally in the form of switches and each key comprises ahousing having a contact therein connected to a source of electricalenergy with the contact being engaged to complete the circuit when thekey is depressed.

Numerous types of switch keys have been devised for introducing datainto electric calculating machines upon the depression of the key. Suchkeys are generally spring switches or snap switches which, upon thedepression of the key, will move a resilient switch contact intoengagement with a stationary contact to close a circuit with the circuitbeing broken when the key is lifted or otherwise returned to its normalposition. A major disadvantage of this type of a switch key is that itis difficult for the operator to ascertain with certainty whether or notthe data which was supposed to have been entered by the depression ofthe key was actually entered. If the key was not sufiiciently depressedby the operator the data will not have been entered since the circuitwould not have been closed.

It has been proposed to correct this difficulty by delaying the breakingof the contact until after a short return movement of the key to itsnormal positon. However, the problem then arose that in quickly strikingone key there was danger of the operator accidentally depressing anadjacent key. The operator thus remained uncertain as to whether thedate was actually entered. This uncertainty could be removed to someextent by some form of a visual indicator actuated when the key wascompletely depressed or by the operator noting the values recorded onthe paper strip.

It is pointed out that the switch key to which the present inventionrelates is of the type which does not remain in its depressed position,but after its release the 3,524,975 Patented Aug. 18, 1970 key willquickly return to its normal position. Thus, the keyboard does notpresent to the operator a pattern of depressed keys which would quicklyindicate to the operator whether or not the data was actually enteredinto the calculating machine.

It is therefore the principal object of the present invention to providea novel and improved switch key assembly for the keyboard of an electriccalculating machine.

It is another object of the present invention to disclose an electricswitch key assembly which will indicate to the operator bothacoustically and by bearing pressure on the key that the data has beenentered into the calculating machine.

It is a further object of the present invention to provide a simplifiedyet etfective arrangement for the mounting of a switch key assembly inthe keyboard of an electric calculating machine.

The present invention essentially comprises a switch key assembly havinga housing in which there is a pair of fixed contacts. Also within thehousing is a contact element having its inner end bent over the fixedcontacts and a movable contact arm has one end mounted on the contactelement bent portion for pivotal movement. The other end of the movablecontact arm has contacts and is movable between the fixed contacts.Depression of the key actuates a key shaft which is slidably mountedwithin the housing and is operatively connected to one arm of an annularlever which is pivotally mounted within the housing. The other arm ofthe angular lever is connected by a spring to the movable contact arm.As a result of this construction, depression of the key to itslower-most or depressed position will pivot the angular lever and alsosnap the movable contact arm through the spring into contact with one ofthe fixed contacts. The key is then moved upwardly to be returned to itsnormal position under the action of a return spring. This upwardmovement of the key shaft will snap the movable contact arm back intoengagement with the second fixed contact.

The clicking noise of the movable contact between the fixed contactswill indicate to the operator that the data has been entered by thedepression of the key. In addition, the varying pressure exerted by thekey will indicate to the operator whether or not the value has beenentered.

The switch key housing is mounted in an opening in the keyboard by meansof cooperating ribs and notches on the housing and keyboard openingrespectively. A resilient member is wedged between the housing and thekeyboard opening to retain the housing in position and to form a tightclosure in the keyboard opening.

Other objects and advantages of the present invention will be apparentupon reference to the accompanying specification when taken inconjunction with the following drawings wherein;

FIG. 1 is a perspective view of a portion of the keyboard showing thekeyboard openings with a switch key housing being mounted in one of saidopenings;

FIG. 2 is an overall perspective view of the switch key housing;

FIG. 3 is a perspective view of the resilient member utilized formounting the housing in the keyboard as illustrated in FIG. 1;

FIG. 4 is a longitudinal sectional view through the switch key housingas illustrated in FIG. 2 with the parts being shown in their normal orresting positions;

FIG. 5 is a sectional view taken along the line 5-5 of FIG. 4; and

FIG. 6 is an overall perspective view of the switching mechanism withinthe housing.

Proceeding next to the drawings wherein like reference symbols indicatethe same parts throughout the various views a specific embodiment of thepresent invention will be described in detail.

Referring to FIGS. 1-3 a switch key assembly according to the preentinvention is indicated generally at 5. This assembly comprises a housing6 having a substantially rectangular cross section as shown. Theassembly 5 is mounted in a carrier plate 7 of the keyboard of theelectric calculating machine. The carrier plate 7 is provided with anopening into which the housing 6 is inserted.

On the upper end of the housing 6 as may be seen in FIGS. 1 and 2 thereare provided external retaining ribs 8 which engage the upper surface ofcarrier plate 7 when the housing 6 is in position as shown in FIG. 1.Spaced below retaining ribs 8 are bosses 9. The distance of the bossesfrom their respective ribs 8 is equal to the thickness of the carrierplate 7.

The carrier plate opening 10 has a pair of notches 11 on opposed edgesthereof as shown in FIG. 1. It may be seen that one notch of each pairis against the edge 13 of the carrier plate opening 10 whereas the othernotch of each pair is spaced from edge 12 of the opening 10.

When the housing 6 is inserted into opening 10, the bosses 9 movethrough the corresponding notches 11 until they are positioned beneaththe carrier plate 7. The housing 6 is then moved laterally against edge12 of the opening. A resilient closure member 14 having tapered edges isthen inserted between opening edge 13 and the housing 6. The closuremember 14 has an external rib 14" which rests against the upper surfaceof carrier plates 7 when the closure member is fully inserted into theopening 10. This closure member not only retains the housing in positionwithin carrier plate opening 10 but also provides a dustproof closurefor this opening so as to prevent the dust and other dirt frompenetrating into the mechanism beneath the keyboard of the calculatingmachine.

The cover member 14 has retaining shoulders 14' which are sprung intoposition to engage the underside of carrier plate 7, thereby securingthe closure member in position.

Proceeding next to FIGS. 4-6 the switching mechanism within the housing6 will be described in detail. The switching mechanism comprises anangular lever 15 which is pivotally mounted on a pin 16 in the innerwall of the housing enclosure 17. The top or cover of the housingenclosure 17 is indicated at 18.

One arm 19 of the angular lever 15 has mounted on its end a tensionspring 20. The other arm of the angular lever has a cylindricalenlargement 21 thereon and is seated in a recess 22 formed in key shaft23. The key shaft 23 is mounted for vertical movement within the housingenclosure 17 and has a key 23 mounted on its upper end which projectsoutwardly of the housing. Thus, any vertical movement of key shaft 23will cause a pivoting movement of angular lever 15.

Also within the housing enclosure 17 there is provided a movable contactspring member 24 having mounted on its lower end a double-faced contact25. The upper end of the contact spring member is bifurcated to form twoends 27 and 27 bent in the manner as illustrated in FIGS. 4 and 6. Theupper edges of the bifurcations 27 and 27 are indicated at 26 and areseated in recesses 28 formed in the undersides of a bent portion of astationary contact element 29 mounted within the housing. With thisarrangement the contact spring arm 24 is electrically connected to thecontact element 29. The tension spring is positioned between thebifurcations and has its other end connected to the contact spring arm24 as shown in FIGS. 4 and 6.

The connection of tension spring 20 to the angular lever 15 and thecontact arm 24 is such that the tension force in the rest position asillustrated in FIG. 4 is to the left of the bearing edge 26 of themovable contact arm v V I T On depression of key 23, the keyshaft 23will move downwardly within the housing enclosure 17 and will pivot theangular lever 15 in the clockwise direction as viewed in FIG. 4. As thetension force exerted by spring 20 becomes positioned to the right ofthe bearing surface 26, the movable contact arm 24 will snap to theright to engage a fixed contact 30 mounted on contact element 31 whichextends outwardly of the housing enclosure.

When the operator releases his finger from key 23', a compression spring32 will return the key shaft 23 to its normal position and accordinglypivot angular lever 15 in a counter clockwise direction. As the forceexerted by spring 20 passes to the left of bearing edge 26 the contactarm 24 will be returned. to its resting position as viewed in FIG. 4with contact 25 being in engagement with fixed contact 33. Fixed contact33 is similarly mounted on contact element 31' which extends outwardlyof the housing enclosure.

In order to minimize the possibility of the bearing edges 26 of themovable contact arm from coming out of recesses 28, the bifurcations 27and 27' may be provided with lugs which extend into recesses 34 and 35formed in the walls of the housing enclosure 17. These recesses wouldhave such a diameter so as to enable the bifurcations to pivot freelytherein but not suflicient so as to enable the bearing edges 26 tobecome removed permanently from the recesses 28.

In order to limit the range of vertical movement of key shaft 23, thekey shaft is provided with ashoulder 36 which moves in a groove formedin an inner wall of the housing enclosure and indicated at 37. Thus, thekey shaft is detained in its resting position by the shoulder 36engaging the upper end of the groove 37 as shown in FIG. 5. The downwardmovement of the key shaft is limited by a felt pad 38 positioned on thetop wall 18 of the housing enclosure 17 as illustrated in FIGS. 4-6.

The contact elements 29, 31, and 31 all of which extend outwardly of thehousing enclosure 17 are electrically connected to the circuitry withinthe calculating machine. The center arrangement of the angular lever,and the tension spring connecting the angular lever to the movablecontact arm assure proper making and breaking of the data introducingcircuits upon the depression and release of the keys on the keyboard.

Thus it can be seen that the present invention provides a switch keyassembly which gives an audible signal to the operator upon theintroduction of data into the machine when the key is depressed. Inaddition, the hearing pressure on the key resulting from the dead'center arrangement indicates to the operator whether or not the data hasbeen entered. The mounting of the switch key assembly in the keyboard ofa calculating machine is extremely effective yet enables the switch keyassembly to be removed for maintenance or other purposes. At the sametime a dust-free closure is provided between the switch key assembly andthe opening in the keyboard.

It will be understood that this invention is subject to modification inorder to adapt it to dilferent uses and conditions and, accordingly, itis desired to comprehend such modification within this invention as mayfall within the scope of the appended claims.

What is claimed is:

1. In an electric calculating machine, the combination of a key boardhaving a carrier plate, there being an opening in said carrier platehaving first and second pairsof opposed edges, said opening havingspaced notches in said first pair of opposed edges, a housing for aswitch key assembly having a cross section corresponding to said openingand mounted therein, the distance between said opening second pair ofopposed edges being slightly greater than the corresponding distance ofsaid housing, external ribs on the top edges of said housingcorresponding to said-first pair of opening opposed edges, a pair ofbosses on said housing spaced below said external ribs a distance equalto the thickness of said carrier plate and insertable in said openingnotches, and a resilient member inserted between said housing and anedge of said second pair of opposed edges to retain said switch keyassembly housing in position and to form a tight closure for saidcarrier plate opening.

2. In an electric calculating machine as claimed in claim 1 with therebeing shoulders on said resilient member insertable through said notchesand fitting under said carrier plate to retain said resilient member inposition.

3. In an electric calculating machine as claimed in claim 1 with saidresilient member having an external shoulder positioned upon the uppersurface of said carrier plate, and a pair of shoulders on said resilientmember spaced below said external shoulders a distance equal to thethickness of said carrier plate and engaging the underside of saidcarrier plate.

4. In an electric calculating machine as claimed in claim 1 with saidresilient member being tapered so as to be wedged between the housingand an edge of the opening. 20

5. In an electric calculating machine as claimed in claim 1 With therebeing a pair of spaced notches in each of said first pair of opposededges, one notch of each pair being at one end of its respective edgeand the other notch of each pair being spaced from the other end of itsrespective edge so that the housing can be moved laterally aftermounting in the opening and the bosses engage the undersurface of thecarrier plate, the resilient member being inserted after the housing ismoved laterally within the opening.

6. In an electric calculating machine as claimed in claim 1 with saidcarrier plate opening being substantially rectangular in shape.

References Cited UNITED STATES PATENTS $3,213,189 10/1965 Mitchell et a1174138 3,226,494 12/1965 Hartz et al. 200-5 STEPHEN J. TOMSKY, PrimaryExaminer

